Use existing get_unused_port() method

There's already get_unused_port() for finding an unused port. Remove the
one in ServoTest and use this one.

BUG=chrome-os-partner:19097
TEST=Run firmware_ECBootTime and pass.

Change-Id: Id72cb0033b8dfe1e8d3b5946ecf790ad0ff29b2a
Signed-off-by: Vic Yang <victoryang@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/50471
Reviewed-by: Scott Zawalski <scottz@chromium.org>
1 file changed